The cultivatioo of narrow·leafed lupins (Lupinus angustifolius L) increases rates of subsoil acidification, and this is thought to be partly related to their pattern of nutrient uptake and H+ jOHexcretion. The main hypothesis of this study was that H+ and OHexcretion is not distributed evenly over the entire length of the root system but is limited to zones where excess cation or anion uptake o...

The liver plays a unique role in nutrient homeostasis. Its anatomical location makes it ideally suited to control the systemic supply of absorbed nutrients, and it is the primary organ that can both consume and produce substantial amounts of glucose. Moreover, it is the site of a substantial fraction (about 25 %) of the body's protein synthesis, and the liver and other organs of the splanchnic ...

Agricultural and urban land use increase nitrogen (N) concentrations in streams, which can saturate biotic demand by plants, algae, and bacteria via assimilative uptake, and by nitrification and denitrification. We studied six streams per year in each of three land-use categories (agricultural, urban, and forested) for 3 yr (n 5 18 streams), and we compared whole-stream N uptake and microbial N...

BACKGROUND AND AIMS Vascular epiphytes have to acquire nutrients from atmospheric wash out, stem-flow, canopy soils and trapped litter. Physiological studies on the adaptations to nutrient acquisition and plant utilization of nutrients have focused on phosphorus and nitrogen; potassium, as a third highly abundant nutrient element, has received minor attention. In the present study, potassium up...

The effects of elevated CO2 on nutrient cycling and selected belowground processes in the closed-canopy sweetgum plantation were assessed as part of a free-air CO2 enrichment (FACE) experiment at Oak Ridge, Tennessee. We hypothesized that nitrogen (N) constraints to growth response to elevated CO2 would be mitigated primarily by reduced tissue concentrations (resulting in increased biomass prod...

Root cortical senescence (RCS) in Triticeae reduces nutrient uptake, nutrient content, respiration, and radial hydraulic conductance of root tissue. We used the functional-structural model SimRoot to evaluate the functional implications of RCS in barley (Hordeum vulgare) under suboptimal nitrate, phosphorus, and potassium availability. The utility of RCS was evaluated using sensitivity analyses...